- Created by: Sarah Stollery
- Created on: 29-03-15 17:40
Atoms and Elements
Protons- Positively charged
Neutrons- No charge
Electrons- Negatively charged
Atoms have no charge overall, they are neutral. The number of protons always equals to the number of electrons in an atom. If some electrons are added or removed then the atom becomes an ion.
In the periodic table, the number above the element is the number of protons and neutrons added together and the bottom number is the atomic number which is the number of protons.
Electrons in an atom whizz around in shells. The first shell holds 2 electrons and the rest of them can only hold 8.
Atoms join together to make compounds. Making bonds involves giving away, taking or sharing electrons. A compound formed with metal and a non metal consists of ions. Compounds formed from non metals consists of molecules.
Getting Metals from Rocks
A metal ore is a rock which contains metal. Most metals need to be extracted using a chemical reaction. Either by reduction or by electrolysis.
Reduction with Carbon-This is exracting a metal chemically by reduction using carbon. When an ore is reduced, oxygen is removed. The position of the metal in the reactivity series determines whether it can be extracted by reduction with carbon. Metals higher than carbon have to be extracted using electrolysis whereas metals below carbon can be extraced by reduction using carbon. When an ore is heated in a furnace it is called smelting.
Electrolysis-Electrolysis is the breaking down of a substance using electricity. It requires a liquid to conduct the electricity, called a electrolyte. The electrolyte has free ions- these conduct the electricity.
Exracting copper-Bioleaching- using bacteria to separate copper from copper sulfide. The bacteria get energy from the bond between copper and sulfur, separating the copper from the ore. The copper can then be extracted by filtering.
Phytomining- Growing plants in soil that contains copper. The copper gradually builds up in the leaves which can then be harvested, dried and burned in a furnace.
Fractional Distillation of Crude Oil
Fossil fuels that, over millions of years, have turned into crude oil can be extracted by drilling and pumping.
Crude oil is a mixture of many different compounds. Most of them are hydrocarbons which are fuels such as petrol and diesel. There are no chemical bonds between the different parts of the mixture so the different hydrocarbons arent chemically bonded.
This means that the keep all their original properties like their condensing points. Crude oil can be separated by fractional distillation. The crude oil is split into separate groups of hydrocarbons.
The fractionating column works continiously, with heated crude oil piped at the bottom. The vapourised oil rises up the column and the various fractions are constantly tapped off at different levels that they condense.